1. Field of the Invention
The present invention relates to a structure for turning upright and supporting stably an openable cover of a shield case of electrical and electronic appliances in an open state.
2. Related Art
Electric and electronic appliances have various kinds of electric and electronic circuits assembled therein and these circuits are shielded lest noise enters from an external electric or magnetic field. Shielding methods include a method that covers the appliance as a whole with a shield case and a method that covers individual components. The invention is directed to the former, that is, the method capable of covering the appliance as a whole.
The shield case is a kind of sealed container formed of a metal sheet capable of shielding the electric or magnetic field. The shield case accommodates therein electronic and electric appliances. To produce, repair and conduct maintenance of the appliance, a cover fitted openably to a case main body is opened. Conventionally, the cover has been detachably set to the case main body with screws and after the screws are removed, the cover is separated from the case main body and is put nearby.
JP-A-2000-56052 describes a “Shield Case” having a structure in which a cover is detachable from a case main body and is fitted in such a fashion as to be capable of being opened and closed relative to a shaft as a center and maintenance and repair can be conducted while the cover is open without being separated from the case main body. In other words, according to this shield case, “the cover is allowed by anchor means to shift between a dosed state and an open state relative to the case main body and to be detachable. When the cover is under the closed state, engagement means anchors the cover to the case main body”.
The cover can be opened and closed with its center positioned at an engagement portion between a projection formed at a rear part of the case main body and a small rectangular opening formed in the cover, and can be fitted and removed, too. Therefore, work operations such as assembly of electronic components and maintenance and repair can be easily conducted inside the shield case while the cover is open without being removed from the case main body. Because the cover is fitted openably through the anchor means, a jig for provisionally placing the cover is not necessary.
However, the projection provided to the case main body must be fitted to the small rectangular open portion formed in the cover and the fitting/removing operation of the cover is troublesome. In addition, the projection provided to the case main body is likely to fall off due to deformation of the side plate, so that the cover often falls off and the opening/closing operation of the cover cannot be made smoothly. In some cases, a metallic sound occurs with the opening/closing operation. The cover is supported in such a fashion that when the cover is opened, the edge of its ceiling plate does not strike the edge or the support side plates of the wall plates and the case main body does not turn down. However, because the cover is opened beyond 90 degrees and is inclined, the case main body is not stabilized and sometimes turns down rearward with the cover.
On the other hand, a substrate having an electronic circuit or circuits constituted thereon is fitted to the cover in some cases and is connected to a substrate fitted to the case main body through a large number of wires. When the cover is opened under such a state, the wires must be long. In a structure wherein the cover is removed from the case main body and is then opened, the length of the wires connecting both substrates becomes much longer. Needless to say, the connecting wires can be separated from the substrates when the cover is opened, but a socket for connection must be removed, and this operation is troublesome.